The present invention is in the field of enzyme proteins that are related to the pyruvate dehydrogenase enzyme subfamily, recombinant DNA molecules, and protein production. The present invention specifically provides novel peptides and proteins that effect protein phosphorylation and nucleic acid molecules encoding such peptide and protein molecules, all of which are useful in the development of human therapeutics and diagnostic compositions and methods.
Many human enzymes serve as targets for the action of pharmaceutically active compounds. Several classes of human enzymes that serve as such targets include helicase, steroid esterase and sulfatase, convertase, synthase, dehydrogenase, monoxygenase, transferase, kinase, glutanase, decarboxylase, isomerase and reductase. It is therefore important in developing new pharmaceutical compounds to identify target enzyme proteins that can be put into high-throughput screening formats. The present invention advances the state of the art by providing novel human drug target enzymes related to the pyruvate dehydrogenase subfamily.
Pyruvate Dehydrogenase Complex, E1 Subunit
The novel human protein, and encoding gene, provided by the present invention is related to the pyruvate dehydrogenase E1-alpha precursor protein (see De Meirleir et al., J. Biol. Chem. 263 (4), 1991-1995 (1988)). The pyruvate dehydrogenase (PDH) complex is comprised of a plurality of each of three different enzymes: pyruvate decarboxylase (E1), dihydrolipoyl transacetylase (E2), and dihydrolipoyl dehydrogenase (E3). Each of these three different enzymes is comprised of multiple subunits; the E1 enzyme is a heterotetramer consisting of two alpha and two beta subunits. The E1-alpha subunit contains the E1 active site and is therefore critical for the functioning of the PDH complex. PDH plays an important role in all metabolically active tissues; however, it plays a particularly critical role in the brain since the brain normally obtains all its energy from aerobic oxidation of glucose.
Genetic defects in the PDH complex are the main cause of lactic acidosis, particularly in children. Furthermore, in the majority of cases, the specific genetic defects leading to lactic acidosis are in the E1-alpha subunit. PDH deficiency due to genetic defects can cause fatal lactic acidosis in newborns and chronic neurological dysfunction and neurodegeneration with gross structural abnormalities in the CNS. PDH deficiency is one of the most common pathologies of mitochondrial energy metabolism. It is common for even heterozygous females to show severe clinical symptoms.
For a further review of the PDH complex, particularly PDH-E 1 and the PDH-E1-alpha subunit, see:
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Enzyme proteins, particularly members of the pyruvate dehydrogenase enzyme subfamily, are a major target for drug action and development. Accordingly, it is valuable to the field of pharmaceutical development to identify and characterize previously unknown members of this subfamily of enzyme proteins. The present invention advances the state of the art by providing previously unidentified human enzyme proteins, and the polynucleotides encoding them, that have homology to members of the pyruvate dehydrogenase enzyme subfamily. These novel compositions are useful in the diagnosis, prevention and treatment of biological processes associated with human diseases.
The present invention is based in part on the identification of amino acid sequences of human enzyme peptides and proteins that are related to the pyruvate dehydrogenase enzyme subfamily, as well as allelic variants and other mammalian orthologs thereof. These unique peptide sequences, and nucleic acid sequences that encode these peptides, can be used as models for the development of human therapeutic targets, aid in the identification of therapeutic proteins, and serve as targets for the development of human therapeutic agents that modulate enzyme activity in cells and tissues that express the enzyme. Experimental data as provided in FIG. 1 indicates expression in humans in teratocarcinoma of neuronal precursor cells, skin, skin melanotic melanoma, muscle rhabdomyosarcoma, brain neuroblastoma, brain, breast, stomach, pancreas adenocarcinoma, uterus serous papillary carcinoma, brain anaplastic oligodendroglioma, colon adenocarcinoma, and fetal brain.